1. Field of the Invention
The present invention relates to a reflecting mirror for an automobile, which reflecting mirror may be advantageously used as a rearview mirror positioned on the fender.
2. Description of the Prior Art
The known reflecting mirror for an automobile located on the outside of the automobile clouds easily when the humidity is high and frosts easily when the temperature drops below the freezing point. In order to remove the cloudiness and frost, the driver has to get out of the automobile and wipe the mirror, which is a tiresome task for him. A known technique for overcoming this drawback is to provide a multilayer light-interference colored mirror, wherein one of the layers is made of a transparent electric conductive material, which layer is electrically energized to generate heat so as to attain a defrost function as is proposed in Japanese Unexamined Patent Publication No. 56-500802. The multilayer light-interference type of mirror, however, must have at least three layers and a black painted layer in order to satisfy the automobile regulation, this number of layers increasing the production cost. There is also known a type of mirror wherein a metallic layer is formed on a glass plate and an electric current is generated in the metallic layer to generate heat so as to provide a defrost function. In this case, in order to generate a large amount of heat, the metal layer must have a thickness as small as possible so that a large electric resistance value is attained. However, a thin metal layer does not have a high ability to reflect light, with the result that it is difficult to see the reflected image on the mirror and that an additional reflecting layer must be provided.